Read the story about the award-winning research

To address the
global threat presented by rising greenhouse gases and climate change, renewable
bioenergy derived from biomass are a necessary part of the equation. But one of
the perks of bioenergy—its potential to be used in many different ways to
replace fossil fuels in generating electricity, heat, transport fuel, and
more—also raises an important and challenging question: How can we get the most out of limited biomass
resources?

“The cost of
bioenergy systems per unit of greenhouse gas reduced is really important
because we all want to do the sensible environmental thing, but we don’t want
excessive cost attached to it,” said Patricia Thornley of the Tyndall Centre
for Climate Change Research at the University of Manchester. “In this paper, we
brought in environmental and economic factors together and used those to show
how different bioenergy systems can contribute in different ways to future
energy systems.”

The Atlas
Award-winning study led by Thornley and her colleagues and reported in the
journal Biomass and Bioenergy sets
out to calculate the true costs and benefits associated with replacing fossil
fuels with bioenergy in various forms and for various applications. Their life cycle
assessment (LCA) approach takes into account entire bioenergy systems,
including every step along the supply chain.

That’s critical
because, if you simply compare the amount of carbon dioxide emitted in burning renewables
versus fossil fuel—coal or gas, for example—Thornley explains, “renewables
look great by comparison. It’s not immediately obvious that renewables also
actually cost energy to produce and therefore have greenhouse gas emissions
associated with their production.”

Their assessment takes
all of those hidden costs into account to provide a solid foundation for making
decisions about the future of energy. The results confirm that bioenergy can
deliver substantial and cost-effective greenhouse gas reductions. But the best
choice among bioenergy systems also depends in important ways on precisely how one
asks the question.

Their assessment
shows that large-scale electricity systems come out on top in terms of absolute
greenhouse gas reductions per unit of energy generated. However, use of wood
chips in medium-scale district heating boilers wins out over electricity in
terms of delivering the highest greenhouse gas reductions per unit of harvested
biomass. Biochar—charcoal derived from biomass and used as a soil amendment—can
deliver the most cost effective greenhouse gas reductions per unit of land
area.

“The key thing is
to be really clear what you are looking for from the outset,” Thornley said,
noting that this is an important moment in time as the European Union weighs
its bioenergy policy. “Policy mechanisms that incentivize reductions in the
carbon intensity of energy may not always result in the best use of the
available resource.”

Collaborators on
the report include Paul Gilbert also from the University of Manchester’s Tyndall
Centre for Climate Change Research along with Simon Shackley and Jim Hammond
from the UK Biochar Research Centre at the University of Edinburgh. The
research was funded by the UK Engineering and Physical Sciences Research
Council as part of the SUPERGEN Bioenergy Consortium and SUPERGEN Bioenergy
hub.

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A conversation with Patricia Thornley

In this podcast, we speak with Atlas award winner Patricia Thornley about bioenergy, its potential
to reduce greenhouse gas emissions, and how their life cycle assessment
approach can be applied in the policy arena.

The following transcript has been edited for clarity
and length.

It’s clear there are various ways in which biomass might be put to use
as an energy source with potential to reduce greenhouse gas emissions. What
issues does this raise?One of the key
selling features of bioenergy as a renewable energy source is that it’s
incredibly flexible. You can use it in lots of different ways. Traditionally
biomass has been used for hundreds of years for heating. But really what we’ve
seen happening over the last 200 years is, as we’ve had the industrial
revolution, we’ve had more and more fossil fuel use resulting in greenhouse gas
emissions. So the key focus has been on trying to reduce those. The thing we’ve
targeted most in the last 20 to 30 years is electricity. You can also use
biomass for chemicals and transport fuel. It has the advantage that you can use
it in lots of different ways, but that can also be in some ways a disadvantage
because what’s been happening in recent times is that people have gotten a bit confused
about what we should use it for. Policymakers have ended up paralyzed because
every week there’s a different paper saying it’s best to do it this way or that
way.

How can we go about making those decisions on the best use of biomass?A key thing is to
be really clear what you are looking for from the outset and what we are
looking for from a bioenergy system is a significant greenhouse gas reduction.
That’s one of the starting points. If we’re looking for a reduction, we’re
looking to replace something. It would be better if it replaces something
fairly carbon intensive in the first place. If you are looking at an industry that’s
already had a long history of development, where things are running relatively
well with fossil fuel, the savings that are available there will be lower. The
way we framed this paper was to look at different ways of asking the question: How
much greenhouse gas can we save with bioenergy? When you ask the question in
different ways, you get different answers about which technology is preferred.
It can depend on a host of other things that sometimes have nothing to do with
the bioenergy system at all. You’ve got to be really clear what you are trying
to achieve.

How does this life cycle assessment approach work?To understand life
cycle assessment, consider the example of a car. If you look at a car, it’s
utility is to drive you from A to B—that’s what a car does. If you look at
petrol consumption and emissions over that period, it’s tempting to look only
at what goes into the car and what comes out. Life cycle assessment goes
further than that. It’s about looking upstream to realize that the car was
produced in a certain way. It took energy to manufacture and material resources.
Also, critically, there’s a disposal required at the end of it. When we talk
about life cycle assessment, it’s from cradle to grave. We look at all the upstream,
usually invisible processes and we look downstream as well at what happens when
this thing reaches the end of its life.In the case of
bioenergy systems, to get a fair comparison of their net impact to the planet,
you’ve got to look at production. In the case of biomass, it’s not only the
infrastructure in the plant you’ve got to consider but also the biomass
feedstock itself. If you have this wood at a power plant, you’ve got to
consider how did it get here? Where did it come from? What were the impacts
along the way? Calculating the greenhouse gas balance of biomass is incredibly
complicated and controversial because there are so many ways of framing the question.
There are many factors to consider. It’s something that’s incredibly
complicated, but incredibly important we get it right because the last thing a
policymaker wants to do is to be involved in instigating a policy instrument
that incentivizes renewable energy and that actually creates more carbon
emissions than it displaces on the fossil fuel side.

How can your work be put to use now?The main significance
of this work is in framing policy development. This is something that’s incredibly
active at the moment. In the European Union there have been efforts to revisit
the bioenergy policy system in recent years. At the moment, we have a system
that says renewable bioenergy systems must meet minimum sustainability criteria,
to achieve minimum greenhouse gas savings. People are developing greenhouse gas
calculators. It’s all very well and good to have a calculator, but if you are
going to do it you need to very carefully tailor the methodology of the
calculator around the objective you want to achieve. In many instances now, I
think that’s not the case. We really need to be very, very careful to be taking
into account the impacts on a common basis.

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About Biomass and Bioenergy

Biomass and
Bioenergyis an
international journal publishing original research papers and short
communications, review articles and case studies on biological resources,
chemical and biological processes, and biomass products for new renewable sources
of energy and materials. The scope of the journal extends to the environmental,
management and economic aspects of biomass and bioenergy.